In general, an organic electroluminescence (EL) device is composed of an anode, a cathode, and one or more organic thin film layers interposed between the anode and the cathode. When a voltage is applied between the two electrodes, electrons from the cathode side and holes from the anode side are injected into a light emitting region. The injected electrons and holes are recombined in the light emitting region to produce an exited state, and when the exited state returns to the ground state, light is emitted.
Since in an organic EL device, a wide variety of luminescent colors can be obtained by using various light emitting materials for the light emitting layer, studies for practical use thereof for a display and the like are actively promoted. In particular, studies of light emitting materials of the three primary colors of red, green and blue are the most actively advanced and intensive studies are being conducted toward higher characteristics.
As such a material for organic EL devices, PTLs 1 to 4 disclose a phosphone oxide compound. However, in the field of organic EL devices, development of new materials is demanded for further enhancement of the performance of the devices.